At present, most of the vehicle suspensions still use the traditional double-tube dampers, the damping coefficients of which cannot be changed under the different driving cycle. As a result, such dampers can only achieve good damping performances in the specific conditions while not be adaptive to different roads, and thus the damping performances thereof are limited. In addition, for most traditional dampers, once the damper is failed, the vehicle will completely lose the capacity of isolating vibration, which has a great influence on the riding comfort and control stability of the automotive.
On the other hand, environmental and energy problems are becoming increasingly serious all over the world. In the case of conventional internal combustion engines, only 16% of the energy is used to drive vehicles, and the remaining energy is consumed by energy-consuming components in the form of heat. Recovery and reuse of energy recovery is an effective way to save energy in the automotive. Some studies have shown the followings: a regenerative braking can increase fuel efficiency by up to 30%; the waste heat recovery can increase fuel efficiency by 10% to 30%; and an energy-regenerative suspension can increase fuel efficiency by 10%.
A linear motor has a simple and compact structure, and provides high efficiency and good anti-electromagnetic performance, wherein there is no radial force present between an armature and a stator. Bose Corporation developed an active energy-regenerative suspension based on linear motor, which can recycle a part of the automotive vibration energy and improves the dynamic performance of the automotive at the same time. However, the linear motor cannot recover the vibration energy and keeps a high level of energy consumption when it outputs an active force. In addition, the Chinese patent application CN201310105535.0 discloses a semi-active energy-regenerative suspension of hybrid electric vehicles, wherein a cylindrical and linear generator is integrated with a traditional passive damper, and wherein a throttle is opened on the piston rod so that the damping force is adjustable. However, the ways to adjust the damping force are complex and unstable. Additionally, the linear motor, which is only used to recover energy, is not adequately used. Therefore, it is urgent to propose a new structure, which is able to recover energy while outputting an adjustable damping force.
Hybrid excitation, a new way of excitation, combines the electric excitation and excitation by a permanent magnet. Compared with a permanent magnet motor, the hybrid excitation motor has the ability to regulate the magnetic field within an air-gap. Meanwhile, compared with the synchronous motor, the hybrid excitation motor has a smaller reactance of armature reaction. Therefore, the present invention proposes the concept to integrate a linear motor based on hybrid excitation with a traditional damper.